Epigenetic regulation of gene expression plays a pivotal role in normal and disease development. A better understanding of epigenetic regulation will lead to better strategies for manipulating cell fate for regenerative medicine, novel epigenetics-based disease markers and biomarkers, and novel therapeutics. Despite of its widespread application in epigenomics, traditional ChIP-Seq technology suffers from several limitations. It requires a large number of cells (typically >106 per experiment), involves extensiv manual handling of the samples, and takes 3-4 days (not including sequencing) to finish. The requirement of a large number of cells prevents application of ChIP-Seq to biologically important but rare cell types, such as stem cells and cells purified from biopsy samples. To overcome such hurdles, we will develop a novel microfluidics-based ChIP- Seq technology that uses two orders of magnitude fewer cells than state-of-the-art protocols and can be completed in hours. As a proof-of-principle, we will apply our transformative technology to profile the epigenomes of hematopoietic stem and progenitor cells (HSPCs) from various stages of embryonic hematopoiesis. Little is known about the dynamics of the epigenome during HSC fate specification since embryonic HSPCs are extremely rare, precluding application of current ChIP-Seq protocols to these cell types. If successful, our proposed technology will revolutionize research in epigenomics by enabling ChIP-Seq studies using rare cells and in fast and multiplex format.